Comparison of the actions of saxitoxin and tetradotoxin on the motor end-plate of frog muscle.
End-plate potentials (e.p.p.) and responses to ionophoretic application of acetylcholine (ACh potentials) have been recorded in frog muscle. Saxitoxin (STX) and tetrodotoxin (TTX) abolished the e.p.p. at concentrations of 10(-8) g/ml. In almost all cases there was no effect on the ACh potentials even when the concentrations were raised, STX to 1.2 x 10(-6) g/ml (3.2 x 1O(-6)M), or TTX to 5 x 10(-6) g/ml (1.5 x 10(-5)M). STX, 10(-6) g/ml (2.7 x 10(-6)M) often caused a slow rise in the frequency of miniature e.p.p., without significant effect on amplitude.
D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001001:Anura; D004594:Electrophysiology; D066298:In Vitro Techniques; D009469:Neuromuscular Junction / Q000187:drug effects* / Q000502:physiology; D011896:Rana temporaria; D013779:Tetrodotoxin / Q000494:pharmacology*; D014118:Toxins, Biological / Q000494:pharmacology*
D014118:Toxins, Biological; D013779:Tetrodotoxin; D000109:Acetylcholine